Step 1: Prepare the Chicken Mixture

1. In a large mixing bowl, combine the ground chicken, chopped spinach, shredded white cheddar cheese, breadcrumbs (if using), minced garlic, onion powder, salt, black pepper, and paprika.
2. Mix until well combined, but do not overmix.

Step 2: Form the Patties

1. Divide the mixture into 4 equal portions and shape each portion into a patty, about 1/2 inch thick.
2. Make a slight indentation in the center of each patty to prevent them from puffing up during cooking.

Step 3: Cook the Burgers

1. In a large skillet or grill pan, heat the olive oil over medium heat.
2. Add the patties to the skillet and cook for about 5–7 minutes on each side, or until the internal temperature reaches 165°F (74°C) and the burgers are golden brown.
3. If using cheese slices, add them on top of the patties during the last minute of cooking to melt.

Step 4: Assemble the Burgers

1. If desired, lightly toast the burger buns on the grill or in a toaster.
2. Place a lettuce leaf on the bottom half of each bun, followed by the cooked chicken patty, sliced tomatoes, sliced red onion, and any additional condiments.
3. Top with the other half of the bun.

Step 5: Serve

1. Serve the burgers immediately with your favorite side dishes, such as sweet potato fries or a fresh salad.